How can HMRC have missed this?

After all the revelations about alleged tax evasion at HSBC’s Swiss Private Bank came a further shocking disclosure.
The whistle-blower at the centre of the scandal, Herve Falciani, offered information on bank account holders in Switzerland to HM Revenue and Customs and the Foreign & Commonwealth Office in 2008.
How can they have missed it?
Well, it doesn’t take a computer forensics expert to realise where the email might have ended up…

credit: Le Monde

Herve Falciani’s 2008 whisleblowing email. Credit: Le Monde